On certain classes of close-to-convex functions

A function f, analytic in the unit disk E and given by , f(z)=z+∑k=2∞anzk is said to be in the family Kn if and only if Dnf is close-to-convex, where Dnf=z(1−z)n+1∗f, n∈N0={0,1,2,…} and ∗ denotes the Hadamard product or convolution. The classes Kn are investigated and some properties are given. It i...

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Main Author: Khalida Inayat Noor
Format: Article
Language:English
Published: Wiley 1993-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Subjects:
Online Access:http://dx.doi.org/10.1155/S0161171293000390
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author Khalida Inayat Noor
author_facet Khalida Inayat Noor
author_sort Khalida Inayat Noor
collection DOAJ
description A function f, analytic in the unit disk E and given by , f(z)=z+∑k=2∞anzk is said to be in the family Kn if and only if Dnf is close-to-convex, where Dnf=z(1−z)n+1∗f, n∈N0={0,1,2,…} and ∗ denotes the Hadamard product or convolution. The classes Kn are investigated and some properties are given. It is shown that Kn+1⫅Kn and Kn consists entirely of univalent functions. Some closure properties of integral operators defined on Kn are given.
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institution Kabale University
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spelling doaj-art-764cff153a9049e3a38be8e24d49f1fc2025-08-20T03:35:16ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04251993-01-0116232933610.1155/S0161171293000390On certain classes of close-to-convex functionsKhalida Inayat Noor0Mathematics Department, College of Science, P.O. Box 2455, King Saud University, Riyadh 11451, Saudi ArabiaA function f, analytic in the unit disk E and given by , f(z)=z+∑k=2∞anzk is said to be in the family Kn if and only if Dnf is close-to-convex, where Dnf=z(1−z)n+1∗f, n∈N0={0,1,2,…} and ∗ denotes the Hadamard product or convolution. The classes Kn are investigated and some properties are given. It is shown that Kn+1⫅Kn and Kn consists entirely of univalent functions. Some closure properties of integral operators defined on Kn are given.http://dx.doi.org/10.1155/S0161171293000390univalentclose-to-convexstarlikeconvolutionintegral operators.
spellingShingle Khalida Inayat Noor
On certain classes of close-to-convex functions
International Journal of Mathematics and Mathematical Sciences
univalent
close-to-convex
starlike
convolution
integral operators.
title On certain classes of close-to-convex functions
title_full On certain classes of close-to-convex functions
title_fullStr On certain classes of close-to-convex functions
title_full_unstemmed On certain classes of close-to-convex functions
title_short On certain classes of close-to-convex functions
title_sort on certain classes of close to convex functions
topic univalent
close-to-convex
starlike
convolution
integral operators.
url http://dx.doi.org/10.1155/S0161171293000390
work_keys_str_mv AT khalidainayatnoor oncertainclassesofclosetoconvexfunctions